Leak test system and method for thermoplastic piping

ABSTRACT

A system and method for leak testing a thermoplastic piping system is disclosed. The leak test system includes a pump assembly having an air pump configured to pressurize a piping system with air, wherein the air pump is configured by design not to output pressure exceeding the piping system design limitations. The pump assembly further includes a pressure sensor, pressure controller, pressure switch, and solenoid valve for maintaining the pressure within the piping system to a prescribed pressure. The leak test system can include tubing for connecting the pump assembly to the piping system, and further include an ultrasonic leak detection device to locate potential leaks identified on the piping system. As such, the leak test system can safely leak test a thermoplastic piping system, including brittle piping, with low pressure air, while being capable of re-pressurizing the system to compensate for pressure variations therein due to leaks and/or other external factors.

FIELD OF THE INVENTION

The present invention relates generally to the leak testing pipingsystems and more particularly to leak testing electrofusion joinedpiping using low pressure air.

BACKGROUND OF THE INVENTION

Leak testing is a staple process employed onto piping systems, includinginstalled systems, to ensure there are no cracks, holes, bad seals, orother openings present, that can result in a respective fluid to leakfrom the corresponding piping system. Presence of leaks can lead topotential safety concerns, as well as translate into economic losses dueto loss of inventory and potential infrastructure damage.

Common leak testing methods include introducing a compressed fluid intoa piping system, either utilizing a pump to provide elevated pressures,or in the case of drain, waste and vent (DWV) systems, fill the pipes toa certain elevation above the pipes with a fluid. The piping system willhave all of its openings blanked (sealed), wherein the pressuredifference between inside and outside the pipe will cause the compressedfluid to escape the piping through any cracks, holes, bad seals, and soon. The compressed fluid can be liquid or gas. One way of detectingleaks using liquid include visually noting liquid bubbling or passingthrough such openings. Compressed gases can include a type of tracergas, such as Helium, wherein the environment surrounding the piping isthen analyzed (using a gas analyzer) to detect the presence of thetracer gas (thereby indicating a leak).

Another example of compressed gas can be air, wherein an ultrasonicanalyzer is used to detect for sounds made by air escaping through suchopenings in the piping system. Alternatively, a soap solution can beapplied to the joints of the piping system, wherein escaping air at anyleaks or openings will create visible soap bubbles, thereby indicatingthe presence and location of such leaks. However, such approachestypically require injecting the gas at high pressure. As such, the useof compressed gases for leak testing brittle piping, such asthermoplastic piping, can be a safety concern considering that if thepiping were to rupture, stored energy could be released rapidly andpotentially cause injury to nearby personnel. Moreover, a ruptured pipe,even if not creating a safety hazard, would require new piping toreplace the damaged equipment.

Conversely, using lower pressured air for leak testing suchthermoplastic piping may also present problems in maintaining sufficientpressure differential for air to escape, since thermoplastic piping issusceptible to expansion, thereby causing the pressure to reduce within(unrelated to the presence of leaks). Temperature fluctuations can alsoreduce or increase the pressure. Moreover, pressure limiting devicesused to limit the pressure of the air can fail, which can result in anoverpressure to the piping system and potentially cause a catastrophicfailure as previously described. Examples of pressure limiting devicesthat may fail include pressure sensors, valves, and relief valves.Additionally, an ultrasonic analyzer may have difficulties in detectinglow-pressure air escaping once the pressure within the piping fallsbelow the limits of the detectors ability to identify escaping air,particularly since the analyzer may be used to identify both thepresence and location of leaks. Thus, unless the system is constantlyre-pressurized, this may potentially result in a missed leak(s), sincethe ultrasonic analyzer has to be maneuvered about the entire pipingsystem searching for the low audible sound of low-pressure air escapingprior to the user ascertaining the presence of a leak.

As such, thermoplastic piping, particularly piping that employelectrofusion welded joints, typically use liquids such as water to leaktest such piping. Examples of piping that use electrofusion weldedjoints can include drainage piping. However, if leaks are discoveredthrough such water-injected leak tests, it becomes very difficult to getall the water out of the piping, specifically the socket joints, whereinit is particularly problematic to re-fuse a joint if there is anyresidual water in the fitting. Similarly, the use of a soap solutionthat is sprayed onto to the piping to help locate leaks on a pipingsystem also result in the introduction of liquids into the electrofusionjoints, thereby potentially rendering the joint non-repairable due tothe presence of liquids.

It should, therefore, be appreciated there remains a need for a leaktest system that addresses these concerns. The present inventionfulfills these needs and others.

SUMMARY OF THE INVENTION

Briefly and in general terms, the present invention provides a systemand method for leak testing a thermoplastic piping system. The leak testsystem includes a pump assembly having an air pump configured topressurize a piping system with air. The pump assembly further includesa pressure sensor, pressure switch, pressure controller, and solenoidvalve for maintaining the pressure within the piping system to aprescribed pressure. The pump, by design, cannot produce a pressure thatexceeds the piping system design limitations. As such, the leak testsystem can safely leak test a thermoplastic piping system, includingbrittle piping, with low pressure air while being capable ofre-pressurizing the piping system to compensate for pressure variationstherein.

More specifically, by example and not limitation, the pressurecontroller is configured to maintain the pressure within the pipingsystem at a prescribed level, e.g., 5 psig, by using relay switches toturn the air pump on/off and open/close the solenoid valve, incoordination with input signals via the pressure switch that is mountedto the pressure sensor. The air pump is designed to be intrinsicallysafe having a maximum pressure output of not more than 15 psig, therebyproviding no risk of overpressure to the piping system if the pressuresensor, switch, and/or controller is to fail. The inherently safe designmay be in addition to any other pressure limiting devices installed onthe leak test system, e.g., relief valves.

In a detailed embodiment, the leak test system can identify the presenceor absence of leaks in a piping system by monitoring the pressuretherein after pressurization. Decreasing pressure indicates the likelypresence of one or more leaks within the piping system. The leak testsystem can further include an ultrasonic leak detection device toidentify the location of leaks on a piping system, after detecting thepresence of such leaks using the pump assembly.

In another detailed embodiment, the air pump can be configured tooperate as a vacuum pump by reversing the inlet and outlet ports. Assuch, a partial vacuum is created within the piping system, and thepresence of leaks can be identified by monitoring if the partial vacuumholds or if the pressure rises. The leak detection system using a vacuumpump can have the same control and operating procedure as when using anair pump, including a controller and pressure sensor, and configured tomaintain a prescribed set point, e.g., −5 psig.

In yet another detailed embodiment, the pressure controller and/orpressure switch can be bypassed, enabling the air pump to runcontinuously so as to safely maintain the piping system pressurized,thereby aiding the ultrasonic leak detection device in locating suchleaks based on the sound of the air escaping therefrom. Similarly, thepressure controller and/or pressure switch can be bypassed to enable thevacuum pump to run continuously.

In yet another detailed embodiment, the leak test system includestubing, e.g., flexible hose or piping, to connect the air pump assemblyto the piping system. The tubing can be secured to an outlet or cleanoutopening on the piping system using a test plug. Test plugs can also beused to blank, or seal, an opening, when conducting the leak test.Different test plugs having different sizes can be used, depending onthe size of the opening on the piping system.

In yet another detailed embodiment, the pump assembly can be placedwithin a self-contained structure, wherein such structure includes aconnection point for tubing to connect the air pump assembly to thepiping system. The structure can further include a display for apressure gauge that can be configured to illuminate upon the detectionof pressure decreasing in a piping system.

In yet another detailed embodiment, the leak testing system can bestored in a portable container that is configured to hold theself-contained structure, the ultrasonic leak detection device withcorresponding noise cancellation headphones, and tubing, e.g., flexiblehose.

For purposes of summarizing the invention and the advantages achievedover the prior art, certain advantages of the invention have beendescribed herein. It is to be understood that not necessarily all suchadvantages may be achieved in accordance with any particular embodimentof the invention. Thus, for example, those skilled in the art willrecognize that the invention may be embodied or carried out in a mannerthat achieves or optimizes one advantage or group of advantages astaught herein without necessarily achieving other advantages as may betaught or suggested herein.

All of these embodiments are intended to be within the scope of theinvention disclosed herein. These and other embodiments of the presentinvention will become readily apparent to those skilled in the art fromthe following detailed description of the preferred embodiments havingreference to the attached figures, the invention not being limited toany particular preferred embodiment disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way ofexample only, with reference to the following drawings:

FIG. 1 is a schematic of a leak test system in accordance with thepresent invention, depicting an air pump assembly connected to a pipingsystem via a flexible hose.

FIG. 2 is a depiction of various sizes of test plugs that are a part ofa leak test system in accordance with the present invention.

FIG. 3 is a depiction of an ultrasonic leak detection device with noisecancelling headphones, as part of a leak test system in accordance withthe present invention.

FIG. 4 is an electrical circuit depiction of the air pump assembly inFIG. 1, depicting the configuration of the electrical circuit connectedto the air pump motor and solenoid valve.

FIG. 5 is a depiction of a leak test system stored in a customcontainer, depicting the air pump assembly disposed within aself-contained structure, and placed alongside the ultrasonic leakdetection device, noise cancelling headphones, and flexible hose.

FIG. 6 is a flow chart of a method in accordance with the presentinvention, depicting the operation of a leak test assembly connected toa piping system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, and in particular FIG. 1, there is showna system and method for leak testing a thermoplastic piping system. Theleak test system 10 includes a pump assembly having an air pump 12configured to pressurize a piping system 14 with air, wherein the airpump 12 is configured by design not to output pressure exceeding thepiping system design limitations. The pump assembly further includes apressure sensor 16, pressure controller 18, pressure switch 30, andsolenoid valve 20 for maintaining the pressure within the piping system14 to a prescribed pressure. The leak test system 10 can include tubing22 for connecting the air pump assembly to the piping system 14, andfurther include an ultrasonic leak detection device (not shown) tolocate potential leaks identified on the piping system 14. As such, theleak test system 10 can safely leak test a thermoplastic piping system14, including brittle piping, with low pressure air, while being capableof re-pressurizing the system to compensate for pressure variationstherein due to leaks and/or other external factors.

With reference now to FIGS. 1 and 2, the air pump 12 can drawsurrounding air through an inlet port and discharge the air via anoutlet port. Additionally, the air pump can be configured as a vacuumpump by reversing the air pump inlet and outlet ports, thereby drawingresidual air and gas from within the piping system to create a partialvacuum therein (further described below). The air pump assembly can beconfigured with an outlet 24 that connects the outlet port (or nozzle)of the air pump 12 to the solenoid valve 20. The outlet can be embodiedin any configuration enabling air flow therethrough, such as piping,tubing, a nozzle, and so on. A tubing 22 can connect the solenoid valve20 to a piping system 14, wherein the tubing 22 can house a pressuresensor 16, a pressure switch 30, and/or a pressure controller 18.

In an exemplary embodiment, the tubing 22 can comprise two sectionsremovably connected to each other. A first section 22 a of the tubing,connected to the solenoid valve 20, can house the pressure sensor 16,pressure switch 30, and/or a pressure controller 18. The second section22 b of the tubing, can be connected to the piping system 14. Theremovable connection between the two sections can be any means thatprovides a pressure tight seal. Each section (22 a, 22 b) can beembodied in any configuration enabling air flow therethrough, such aspiping, flexible hose, and so on. For example, the second section 22 bcan include a flexible hose that connects to the piping system 14 usinga test plug 26, which is secured within/about an open outlet or cleanoutopening (an access point for cleaning/unplugging) on the piping system.The test plug 26 can be secured to the flexible hose and piping system14 via a screwed connection. Moreover, the test plug 26 can be securedto the piping system by being inserted within either a pipe fitting,such as a socket or cleanout fitting, or pipe ID or flange, wherein whenthe test plug is expanded, creates a pressure tight seal with the pipingsystem that can withstand the pressure created by the air pump. The testplug 26 configured for the leak test system can vary in size, so as toaccommodate different available opening sizes found on a given pipingsystem. Examples of test plug sizes can include 2″ (26 a), 3″ (26 b), 4″(26 c) pipe sizes, or any size to match a corresponding pipe size.Alternatively, a hard pipe connection such as a flange, can be used toconnect the second section 22 b with the piping system 14. In additionor alternatively, the first section 22 a can directly connect to thepiping system 14, via a test plug.

The piping system can comprise any type of material, including brittlethermoplastic piping such as PVC, CPVC, PP, and PVDF among others. Morespecifically, the leak test system 10 is particularly useful for pipingthat employ electrofusion welded joints, such as Fuseal® piping, PProSeal™ piping, and some double containment systems, e.g., FusealSquared®.

With continued reference to FIG. 1, prior to connecting an air pump 12to a piping system 14, all open ends in the piping system 14 mustblanked, i.e. isolated or closed-off using test plugs 28 or valves, soas to ensure that air cannot otherwise escape the piping system 14. Thetest plugs 28 can be secured to the piping system similar to how thetest plug 26 is secured to the piping system. Moreover, test plugs 26and test plugs 28 may be the same type, wherein an integral centerfitting enables for air to flow through test plugs 26. Smaller sectionsof a large piping system may be tested separately so as to easier locateany potential defects, provided such smaller sections can be isolatedfrom the other sections of the piping system.

Activating an air pump 12 connected to a piping system 14 will introduceair into said piping system, causing the pressure therein to rise. Asaforementioned, the air pump assembly can include a pressure sensor 16,pressure switch 30, controller 18, and solenoid valve 20 that limit andcontrol the pressure rise within the piping system 14. Although othervalve types can be used, such as a butterfly valve or gate valve, asolenoid valve is preferred due to its fast response time, particularlysince it needs to open and close with pump actuation/shutdown.Specifically, the valve 20 can enable or restrict air flow from the pump12 and outlet 24 to the piping system 14. The pressure sensor 16 isdisposed downstream of the solenoid valve 20 and configured to detectthe pressure within the tubing 22, which is reflective of the pressurewithin the piping system 14. Moreover, the pressure controller 18 caninclude a pressure gauge (not shown), thereby providing visualindication of the pressure within the piping system 14, as detected bythe pressure sensor 16. Alternatively, a separate pressure gauge can beincluded on the tubing 22, providing visual indication of the pressurewithin the piping system.

Referring now to FIGS. 1 and 4, the controller 18 can be electricallycoupled to the pressure sensor 16, and further be electrically coupledto the air pump 12 and the solenoid valve 20 via relay switches (notshown on FIG. 1) configured on the controller 18. As such, thecontroller 18, based on the detected pressure from the pressure sensor16, can be configured to control the air pump 12 operation and solenoidvalve 20 positioning. Specifically, the controller 18 can start/stop theair pump 12, and/or open/close the solenoid valve 20, so as to maintaina prescribed pressure within the piping system 14. More specifically, apressure switch 30 mounted to the pressure sensor 16 can be activatedupon the prescribed pressure being measured by the pressure sensor 16,such that the controller 18 receives a signal to shut down the pump 12and/or close the solenoid valve 20 (via the relay switches). Conversely,the controller 18 and pressure switch 30 can be bypassed to enablecontinuous pump operation (further described below).

The prescribed pressure for leak testing can vary by piping system. Forexample, the plastic piping industry has adopted a 5 psig limit for allbrittle materials, which has been determined to be a safe pressure fordetecting leaks, and high enough for locating leaks when spraying soapywater onto a piping system.

In an exemplary embodiment, the controller 18 and pressure switch 30 canbe set to maintain a prescribed pressure, e.g., 5 psig, within thetubing 22 and piping system 14. As aforementioned, once the pressuresensor 16 detects a pressure of 5 psig within the piping system 14, thepressure switch 30 is activated, sending a signal to the controller 18to shut-off the air pump 12 and/or close the solenoid valve 20, viarelay switches configured on the controller 18. The piping system 14 isthus completely isolated, enabling the pressure therein to be displayedand monitored on the controller 18 via the pressure sensor 16 since itis disposed downstream of the solenoid valve 20. The length of time fora pump assembly to pressurize a piping system can vary, depending on thepump output, and volume within the piping system. In an exemplaryembodiment, the air pump 12 can be configured with an output of 5 CFM,which would take about 5 minutes to pressurize 300 ft of 6″ piping to 5psig.

In the event that the pressure sensor 16, switch 30, and/or controller18 fail to correctly operate, resulting in a failure to stop the airpump 12 and close the solenoid valve 20 after the pressure has reachedthe respective setpoint (prescribed pressure), there is no risk ofoverpressure to the piping system since the air pump 12 by design islimited in the maximum pressure that can be outputted into a pipingsystem. This inherently safe design may be in addition to any otherpressure limiting device(s) disposed on the system, e.g., a reliefvalve, which may be susceptible to failure. The maximum output pressureof the pump can take into account the piping system 14 designlimitations, such that there is no risk of overpressure to the pipingsystem. For example, the maximum design pressure for piping systems canbe 50 psig or more depending on size and material. In an exemplaryembodiment, the air pump 12 can be designed to not be able to producemore than 15 psig, i.e. the maximum output pressure of the pump is 15psig. As such, the air pump 12 cannot generate sufficient energy tocause a pipe failure for such piping systems.

The controller 18, using the pressure switch 30, can also restart theair pump 12 and/or open the solenoid valve 20 to increase the pressurewithin the piping system 14. For example, during the initialpressurization by the air pump assembly, the piping system 14,particularly those made of thermoplastic material, may undergo pipingexpansion, and/or experience temperature fluctuations, such that thepressure within the piping system may decrease below the controllerpressure setpoint (prescribed pressure). As such, upon the pressuresensor 16 detecting the pressure in the system falling below theprescribed pressure, the pressure switch 30 will be deactivated,enabling the controller 18, via the relay switches, to restart the airpump 12 and/or open the solenoid valve 20, and thereby re-pressurizingthe system up to the prescribed pressure (controller pressure setpoint).

As such, the pressure controller 18 is configured to maintain aprescribed pressure within the piping system 14. In an exemplaryembodiment, the on/off pressure band for the controller 18 can be +/−1.5psi, such that the pressure within the system can be stabilized between3.5 psi and 6.5 psi. An example of a pressure sensor 16 and controller18 used by the air pump assembly is the Signet 2450 pressure sensor andSignet 9900 controller.

A piping system typically requires a minimum time to have lapsed afterfirst reaching a controller pressure set point in order to achievepressure stabilization. Such minimum time can vary, e.g., one to fiveminutes. Thus, pressure variations occurring after such minimum time haslapsed is deemed to be due to reasons other than pressure stabilization.Once the pressure in the piping system stabilizes, the pressure withinthe piping system 14 can be monitored for a prescribed time, e.g,several minutes, via a pressure gauge, that can be located on thecontroller 18 and thereby electrically coupled to the pressure sensor16. If the pressure holds, i.e. does not decrease, then the pipingsystem 14 is leak free. Conversely, a decrease in pressure, resulting inthe pump to be cycled, i.e. turn on and off as the system loses pressureand re-pressurizes, indicates the likely presence of one or more leaksin the piping system 14. Frequent pump cycling may indicate a largesized leak, while pump cycling occurring over several minutes mayindicate a small leak.

Referring now to FIGS. 1 and 3, the leak detection system 10 can furtherinclude an ultrasonic leak detection device 32 for locating leakspresent on a piping system, by detecting the sound of air escapingthrough such leaks. Thus, the ultrasonic leak detection device (ULDD) 32can be used by the leak detection system 10 upon the air pump assemblyidentifying the presence of leaks in the piping system 14. The ULDD 32can detect air escaping from small bore holes, such as air escaping at 5psig from a hole as small as 0.005″. As aforementioned, the air pumpassembly, using the controller 18, can be used to maintain the pressurewithin the piping system at 5 psig, to aid the ULDD 32 in detecting thesound of air escaping. Alternatively, a bypass switch can be includedwith the air pump assembly to enable the air pump 12 to bypass thecontroller 18 and/or pressure switch 30, and thereby run continuously.As such, the air pump 12 can then provide a continuous pressure to thepiping system 14, making it easier for a ULDD 32 to detect the sound ofthe air escaping. Moreover, having the air pump 12 run continuouslyavoids it from having to continuously cycle between on and off, whichcould potentially damage the air pump motor. For example, a large sizedleak may result in the pump to continuously cycle on and off every fewseconds. The ULDD 32 can also be embodied as a handheld detection devicewith noise cancelling headphones 34, thereby enabling a user to move theULDD 32 along the piping system 14 in locating a leak(s).

Once the leak(s) have been identified, such piping can be repaired whilestill dry. Thus, the risk of exposing leaks on the piping system towater due to any subsequent hydrostatic pressure tests performed iseliminated. As aforementioned, the leak detection system seeks tominimize the exposure of leak(s) to water, particularly forelectrofusion welded joined piping, since it becomes very difficult tore-fuse a joint if there is any residual water in the fitting.

As aforementioned, the air pump can be also configured as a vacuum pumpby reversing the inlet and outlet ports of the pump, i.e. connecting theoutlet 24 to the pump inlet port, thereby enabling the pump to drawresidual air and gas from within the piping system. A partial vacuumwill subsequently be created within the piping system, wherein thecontroller 18 and pressure switch 30 can have a setpoint of −5 psig, soas to maintain said partial vacuum. As such, the leak detection systemwill identify leaks based on determining whether the partial vacuumholds, or whether the pressure increases. The vacuum pump is similarlylimited to creating a half vacuum, or −7.5 psig, for which the pipingsystem is designed to withstand, in the event the pressure sensor,pressure switch and/or controller fail to maintain a prescribed partialvacuum. In addition to or alternatively, an additional valve may beincluded enabling the inlet and outlet ports to be reversed.

The leak detection system using a vacuum pump will have similar controland operating procedures as previously described with the air pumpconfiguration. For example, the controller 18 will be configured tostart/stop the vacuum pump and/or open/close the solenoid valve, usingthe pressure switch 30, so as to maintain the prescribed partial vacuumsetpoint, e.g., −5 psig. In this configuration, the pressure sensor willbe upstream of the solenoid valve and still be reflective of thepressure within the piping system. The piping system may also be subjectto a period of stabilization, e.g., one to five minutes, due to pipingconstriction and temperature fluctuations. After stabilization, thepressure is monitored for a prescribed time to determine if the partialvacuum holds. The continual rise in pressure within the piping systemindicates the likely presence of leaks therein, wherein an ultrasonicleak detection device can be used to locate such leaks by detecting airseeping into the piping system.

Referring now to FIGS. 1 & 5, the air pump assembly can be housed withina self-contained structure 36, enclosing the air pump 12, outlet 24,pressure sensor 16, controller 18, and solenoid valve 20. The structure36 can also enclose the first section 22 a of the tubing 22. Moreover,the structure 36 provides a display 38 for a digital pressure gauge,thereby visually indicating the pressure detected by the pressure sensor16. The display 38 can be configured to illuminate when detecting apressure drop in the piping system 14 (or increase in pressure, whenusing a vacuum pump). The structure 36 includes a connection nozzleenabling the second section 22 b of the tubing 22 to connect to thefirst section 22 a. Moreover, the structure 36 includes, externally, apower switch for the air pump assembly, a switch to turn the air pumpon, and a switch that enables the controller and pressure switch to bebypassed, thereby allowing for continuous pump operation and air supply.The structure 36 can be stored and secured within a container 40, whichalso includes space to store tubing 22, e.g., the second section 22 b ofthe tubing 22, an Ultrasonic Lead Detection Device 32, and correspondingnoise cancelling headphones 34. Handles 42 can be included with thecontainer 40, thereby providing a compact leak detection system 10 thatis portable.

Referring now to FIG. 6, an exemplary flow chart depicting the methodfor leak testing a brittle piping system with air is shown. First, allthe openings of a piping system are sealed, or blanked 200. Next, a leaktest system is connected 202 to the piping system via tubing. The airpump is subsequently turned on, wherein the piping system is pressurized204 with air. The pressure switch and controller will then turn off(206) the air pump and close the solenoid valve once a prescribedpressure (e.g., 5 psig) is reached. The controller will subsequentlycycle (208) the air pump on/off, and the valve open/close, until thepressure within the piping system stabilizes (210). Subsequently, thepressure within the piping system is monitored (212), for a prescribedtime and using a pressure gauge, to determine if it holds. If thepressure within the piping system holds (214), then the piping system isleak free. If the pressure decreases, the air pump is turned on (216)and the solenoid valve is opened, while the controller is bypassed,enabling for continuous operation of the pump. Subsequently, anUltrasonic Leak Detection Device is used (218) to locate leaks on thepiping system. Any leaks located are repaired (220), wherein the pipingsystem is again leak tested to ensure no leaks remain.

It should be appreciated from the foregoing that the present inventionprovides a system and method for leak testing a thermoplastic pipingsystem. The leak test system includes a pump assembly having an air pumpconfigured to pressurize a piping system with air, wherein the air pumpis configured by design not to output pressure exceeding the pipingsystem design limitations. The pump assembly further includes a pressuresensor, pressure controller, pressure switch, and solenoid valve formaintaining the pressure within the piping system to a prescribedpressure. The leak test system can include tubing for connecting thepump assembly to the piping system, and further include an ultrasonicleak detection device to locate potential leaks identified on the pipingsystem. As such, the leak test system can safely leak test athermoplastic piping system, including brittle piping, with low pressureair, while being capable of re-pressurizing the system to compensate forpressure variations therein due to leaks and/or other external factors.

The present invention has been described above in terms of presentlypreferred embodiments so that an understanding of the present inventioncan be conveyed. However, there are other embodiments not specificallydescribed herein for which the present invention is applicable.Therefore, the present invention should not to be seen as limited to theforms shown, which is to be considered illustrative rather thanrestrictive.

Although the invention has been disclosed in detail with reference onlyto the exemplary embodiments, those skilled in the art will appreciatethat various other embodiments can be provided without departing fromthe scope of the invention, to include any and all combination offeatures discussed herein.

What is claimed is:
 1. A method for leak testing a thermoplastic pipingsystem, comprising: isolating a piping system; connecting a leakdetection system to the piping system, the leak detection systemcomprising: an air pump connected to an outlet, the air pump configuredwith a maximum pressure output of not more than 15 psig, a valve coupledto the outlet for enabling and restricting air flow from the outlet; atubing coupling the valve to the thermoplastic piping system, tointroduce air within said piping system; a pressure sensor coupled tothe tubing to measure the pressure therein and within the piping system,the pressure sensor disposed downstream of the valve, a pressure switchmounted to the pressure sensor and configured to be activated based on aprescribed pressure measured by the pressure sensor, a pressurecontroller electrically coupled to the pressure sensor and pressureswitch, the pressure controller having one or more relay switcheselectrically coupled to the air pump and valve, such that the pressurecontroller is configured to automatically maintain a prescribed pressurewithin the piping system, to account for pressure variations therein,and a pressure gauge electrically coupled to the pressure sensor, tovisually indicate the measured pressure; activating the air pump topressurize the piping system; stabilizing the piping system to aprescribed pressure using the controller to control air pump operationand valve positioning; monitoring the pressure within the piping systemfor a prescribed time via the pressure gauge; restarting the air pumpupon determining the pressure cannot hold in the piping system, thecontroller bypassed to allow for continuous pump operation; locatingleaks on the piping system using an ultrasonic leak detection device. 2.The method as defined in claim 1, further comprising: repairingidentified leaks; and re-testing the piping system with the leakdetection system.
 3. The method as defined in claim 1, wherein theprescribed pressure is between 3.5 psig and 6.5 psig.
 4. The method asdefined in claim 1, wherein the leak detection system further comprisesa bypass switch to bypass the controller, enabling the air pump tocontinuously run and pressurize the piping system.
 5. The method asdefined in claim 1, wherein the leak detection system further comprisesa self-contained structure housing the vacuum pump, the inlet, a firstsection of the tubing coupled to the pressure sensor, the pressureswitch, the pressure gauge, the valve, and the pressure controller, theself-contained structure including a digital display for the pressuregauge.
 6. The method as defined in claim 1, wherein the leak detectionsystem further comprises a portable container configured to house theself-contained structure, a second section of the tubing, and anultrasonic leak detection device with corresponding noise cancellingheadphones.